1. Field of the Invention:
The present invention relates to infrared and optical systems. More specifically, the present invention relates to systems and methods for effecting steering of infrared and optical beams.
2. Description of the Related Art:
For many applications, there is a need to generate images optically. Military and commercial aircraft applications, for example, utilize systems which transmit and/or receive infrared, near-infrared, optical or other electromagnetic energy. The input and/or output beams must be steered in a desired pointing direction.
For beam steering, the prior art includes steering mirrors, pointing gimbals and monochromatic electro-optical, beam steering mechanisms. Steering mirrors require output windows many times the size of the system optical entrance pupil to scan over a large field of regard. Unfortunately, the mirror form factor requirements greatly increase the size of the sensor package.
The gimbaled approach involves use of an imaging system mounted in a dome that is gimbaled to provide a desired pointing angle. The gimbals must point the entire sensor to scan the field-of-regard. Unfortunately, for aircraft applications, this requires a mirror below the platform line, which necessitates a hole in the platform. In addition, the dome and optical assembly is bulky, typically requires considerable volume, and has a radar cross-section which tends to increases the observe-ability of the vehicle.
The monochromatic electro-optical, beam steering approach involves the use of a liquid crystal as the manipulated medium. This approach relies on a diffractive grating pattern in a liquid crystal array. Displacing the grating causes a phase delay that steers the beam. Unfortunately, this approach only operates effectively for monochromatic or near-monochromatic light sources. For non-monochromatic light sources, this approach causes undesirable color dispersion.
Accordingly, a need exists in the art for small, compact optical scanning system with small aperture size requirements, wide field-of-regard and minimal color dispersion characteristics.